I've found Amazon itself is usually eerily fast and accurate in delivery considering how many orders they process. Marketplace sellers, on the other hand, vary wildly.

I order a lot of stuff from Amazon and the only real problem I've had with Amazon itself was when I recently ordered new caps for the sewer connection on the TT, and that was more of a warehouse mixup.  The existing caps are fairly tight and I have a hard time getting them off. I specifically ordered new caps with little "wings" on the sides for extra grip/leverage. They wound up sending me the exact same thing I have right now, which is clearly not the same item as pictured.  At least the return process is about as pain free as one could imagine it being.

I did have a problem with a marketplace seller who sent me a hard drive with virtually zero packaging and it was dead as a door nail.  After trying to communicate with him for a month, Amazon refunded my money and apparently froze his account until he responded to them.  Despite all the inconvenience, I still had to wind up eventually sending the DOA hard drive back to him. I intentionally packed it up the exact same way he shipped it to me, except I then put it inside another box with appropriate packaging so he couldn't say *I* packed it poorly.  It was frustrating I had to pay for failures on the seller's part, but I just wanted it done with.

I just had a very weird fast delivery and Amazon was great about it -- so far.

I thought some last ditch effort could be made to help my (now deceased dog) Ivan on Monday, Memorial Day, around 8 PM and ordered something from them that was recommended by a homeopathic practicioner. By 8 AM, I knew it was hopeless to think anything would help the poor boy and called Amazon to cancel the order. They said it was too late and the order had been shipped USPS. I told the rep that was unusual since it was a U.S. holiday (and I don't think she was in the U.S.), but she told me it would arrive on Thursday and to either refuse it or to get a return label from Amazon and send it back. Amazingly, it arrived Wednesday - a day "early" - and I was able to refuse it. Amazon actually followed up via email and I told them the item was refused. They said that a credit would show up in 2-3 days on my account. Voila! It was there. Such a great customer service experience.

I think if you filter so you only see "prime" products, that should limit you do products provided or fulfilled by Amazon.  I'm not sure whether that filter option shows up if you don't have prime, though.